Bistable ball-armature contact

ABSTRACT

A bistable ball-armature contact having a ball-armature which can be brought to two switching positions by a magnetic flux variation, and which is held in one of the switching positions in the absence of an external magnetic flux by means of at least one permanent magnet for each switching position. The said magnets are polarized in the same direction and encompass the ballarmature, the electrical contacts being formed by two collinear contact strips at one side of the magnets and a supporting strip, situated parallel to the contact strips, for the ball-armature at the other side of the magnets.

United States Patent 1191 Greve et al.

1451 Feb. 13, 1973 ReierencesCited- 541 BISTABLE BALL-ARMATURE CONTACT [75]" lnventorszi Reinhard'Cornelis Greve; Hendrik 1 Johannes De Jong, both of Hilver- 7 sum, Netherlands [73] Assignee: UQS. Philips Corporation, New

- York,.N.Y.

22 Filed: Sept. 15,1971

{30] Foreign Application Priority Data Sept. 23, 1970 Netherlands 7014026 [-52], U. S. CI.. 335/l79, 335/83 [5.1] l nt.Cl....'. ..H0lh5l /24 53 .;Field o Search..'....335 /l79, 80,80, 81, s2, s3, v 335/l,2,196

w H UNITED STATES PATENTS 2,794,178 5/1957 ambus ..335/82 1/1956 Buckingham ..335/83 5/1958 Reynolds ..335/179' Primary Examiner-Harold Broome Attorney-Frank R. Trifari Q ABSTRACTH A bistable baILarmature contact having a ball-armature which can be brought to two switching positions by a magnetic flux variation, and which is held in one of the switching positions in the absence of an external magnetic flux by means of at least one permanent magnet for each switching position. The said magnets are polarized in the same direction and encompass the ball-armature, the electrical contacts being formed by two collinear contact strips at one side of the magnets and a supporting strip, situated parallel to'the contact strips, for the ball-armature at the other side of the magnets.

11 Claims, 5 Drawing Figures REINHARD C. GR VE H NDRIK J. DE ONG BISTABLE BALL-ARMATURE CONTACT This invention relates to a bistable ball-armature contact which is accommodated in a preferably hermetically closed envelope and whose ball-armature can be displaced by :a magnetic flux variation to two switching positions, the ball armature being held in each of these switching positions by at least one permanent magnet.

In bistable ball-armature contacts of the kind set forth, it is known (from the German Pat. Specification No. 1,116,815) to arrange the ball-armature between two oppositely polarized permanent magnets. One switching position is then formed by two collinear contact strips at one side of the ball-armature, while the other switching position also is formed by two collinear contact strips which are situated at the other side of the ball-armature'and which extend parallel to the former contact strips. The contact is made by causing the ballarmature to bridge the gap between two collinear contact strips. In the absence of coil energization, the ballarmature is held in each switching position by the field of both permanent magnets.

One of the drawbacks of the described known bistable ball-armature contact is that the permanent magnets have to be polarized before they are mounted in the ball-armature contact, since polarization of already fitted magnetizable material in mutually opposite directions is very difficult due to the comparatively small distance between both magnets. The prepolarized permanent magnets must be treated very carefully so as to avoid attraction of metal particles which might give rise to insufficient reliability of the ball-armature contact. Moreover, the temperature required for moulding-in the contact strips may cause depolarization of the magnets. If the field strength of the permanent magnets does not have exactly the correct value, readjustment after mounting is very difiicult due to the already mentioned small distance between the magnets, which might cause a comparatively high rejection percentage.

The invention has for its object to eliminate the described drawbacks.

To this end the invention is characterized in that the flux of the first permanent magnet corresponding to one switching position passes mainly through a first contact strip and a supporting strip of electrically conducting material for the ball-armature, said supporting strip being parallel with said first contact strip and common to both switching positions, while the flux of a second permanent magnet corresponding to the other switching position passes mainly through a second contact strip which is substantially collinear with the first contact strip, and the said supporting strip, the permanent magnets being polarized in the same direction.

In order that the invention may be readily carried into effect, some embodiments thereof will now be described in detail, by way of example, with reference to the accompanying diagrammatic drawings, in which:

FIG. 1 is a longitudinal sectional view of an embodiment of a bistable ball-armature contact according to the invention, used in a ball-armature relay.

FIG. 2 is a partly broken away plan view of two bistable ball-armature contacts according to FIG. 1, accommodated in a common envelope and used in a double ball-armature relay.

FIG. 3 is a diagrammatic representation of the variation of the magnetic fluxes for one of the switching positions of the ball-armature relay shown in FIGS. 1 and 2.

FIG. 4 is a longitudinal sectional view of a bistable ball-armature contact according to the invention, used in a further embodiment of a ball-armature relay.

FIG. 5 is a partly broken away plan view of a triple ball-armature relay according to FIG. 4.

The bistable ball-armature relay shown in FIG. 1 comprises two permanent magnets l and 3 which are polarized in the same direction, a ball armature 5 of a magnetically and electrically conducting material being situated therebetween. The magnets l and 3 of, for example, a ceramic magnetic material constitute a space between two collinear contact strips 7 and 9, each of which extends on one side of the ball-armature 5, and a supporting strip 11 which is common to both switching positions. The supporting strip 11 constitutes a roller path for the ball armature 5. The contact strips 7 and 9,

and also the supporting strip 11, are made of magnetically and electrically conducting material such as, for example, nickel-iron. The ends 13 and 15 of 'the contact strips 7 and 9 which face the ball armature 5 are preferably bent in the direction of the supporting strip 11 so as to obtain a smooth abutment for the ball armature 5. In order to provide a force on the ball-armature 5 which is always sufficiently large and which is directed towards the supporting strip 11, it is advantageous to situate the point of contact of the ends 13 and 15 with the ball-armature 5 below the center of the ball-armature.

The contact strips 7 and 9, the supporting strip 11 and the permanent magnets l and 3 are accommodated in a hermetically closed envelope 17 of, for example, ceramic. The envelope 17 is provided with an aperture 19 which is closed off by a lid 21 afterthe ball armature 5 has been mounted. The ball armature 5 is mounted prior to the polarizing of the permanent magnets l and 3. In order to reduce bouncing of and noise from the ball-armature contact, the ball armature 5 may be provided with a mercury layer. The ends 13 and 15 of the contact strips 7 and 9 are preferably provided with diagonally opposite chamfers 23 and 25 (see FIG. 2). The chamfers 23 and 25 serve to make the ball-armature 5 move diagonally with respect to the longitudinal axis of the ball-armature contact. The ball-armature 5 is thus rolled loose from the relevant contact strip when the electrical contact is broken so that a larger release force is obtained. In addition, a spinning motion is imparted to the ball-armature so that the entire surface of the ball armature is used. This results in a prolonged service life and also prevents pitting and the formation of craters. In order to avoid the risk of contact between the ball-armature 5 and the ceramic envelope, a U- shaped strip 27 of, for example, stainless steel is preferably secured to the supporting strip 11. Outside the ceramic envelope 17 there is situated an energizing coil 29 mounted on a coil former 31. A soft-iron magnetic short circuit 33 is preferably provided inside the coil former 31.

The magnetic flux variation required for switching over the ball-armature contact can also be produced by means of a permanent magnet which is arranged in a displaceable manner.

. 3 The ball-armature relay, described mainly with reference to FIG. 1 is particularly suitable for multiple 1 execution. Using reference numerals corresponding to 'comb of contact strips fr om a strip of material andby ;accommodatingthis-comb inits entirety in a ceramic envelope. After the envelope has been formed, the contact strips are mutually broken so that the contactdistance between'the contact strips is accurately maintained in a simple manner when-the envelope is fitted. By using continuing {bar-shaped or annular permanent magnets, the mounting of the contact is considerably simplified since a separate magnet is not required for each contact in,the'multipleexecution, but a comparatively long perrn'anentmagnet, givenportionsof which are associated with different contacts. It will be obvious that an energizing coil which is-common to all ball-ar- 1 mature contactsiispreferably,used in a'multiple'ba'll-armature contact (seeFICi- 2)- g FIG. 3 is a diagramma'tic representation ofthe variation of the magnetic. fluxesinaball-armature relay having a ball-armaturecontactaccording to the invention. FIG. Sshows the-magnetic fluxesat-the instant that the electrical contactrbetwecn thecontact strip 7 and the supporting strip 11 ,is vto be broken and the contact between thecontactfstrip;9;-and the-supporting strip 11 is-to be made. when-.thekcoilis notenergized, the hold flux 4;, originatingfromithe permanent magnet 1 ex- I ceedsthe fluxrb}, originatingyfro m the permanent magnet 3 due t0. athe larger. airpath in the (magnetic circuit of the permanentmagnetsxwhemthe coil 29 .is energized 'in the directio'nshown ,in ;FlG.. 3, a flux n5, is generated by thegcoil 29,{said;flux, ,,counteracting the flux tp and am,plifyir g1the flux., Consequently, the ball-armature} -is displacved Itocontactstrip 9 and establishes an electricaliconnection-tbetween the contact strip 9 and the supporting strip 11. The contact is changed overjby reversing-the direction of energizing current in thecoilf A The further embodimentof a bistable ball-armature relay in which abistable, ball-armaturecontact according to the invention :is used,.and which is illustrated in FIGS, 4 and 5, comprisestwo permanentfmagnets 35 and 37 which are polarizedinthe-same direction along witha ball-armature 39.,of'magnetically andelectrically conducting material which -.is situated .therebet'ween.

Two collinear cOntactstrips-A Land 43 are separated by the magnets ,35 and .37 from asupportingfstrip 45 which is .common to both switching positions. The "contact I strips 41 and43jand thesupporting strip 45-are made of electrically and magneticallyconducting material such as, for example, nickehiron. The ends 47 and 49 of the contact strips .41 and 43.:facingthe ball-armature 39 are benttowards thesu pOrtingstripAS andforman abutment for .the ball armature ,39. Neartheirends '47 and '49, the contact strips) 41 .and 43-, are provided with tact strips 41 and 43, the supporting strip 45, the permanent magnets 35 and 37 situated therebetween, and

1 theball-armature 39 are accommodated in a hermetically closed envelope 57 of, for example, ceramic. Around the hermetically closed envelope 57 an energizing coil 59 is provided. Between the energizing coil 59 and a soft-iron magnetic short circuit 61 externally provided around the coil, an electrically insulating layer'63 is provided so as to prevent the contact strips 4l and43 from being electrically short'circuited by the magnetic short circuit 61.

' The bistable ball-armature relay described mainly with reference to FlG. 4 is particularly suitable for multiple execution. (Compare with the ball-armature relay shown in FIG. 1). FIG. 5 is a partly broken away plan view of a triple ball-armature relay according-to FIG. 4 and is provided with corresponding reference numerals for the sake of simplicity. The triple ball-armature relay shown in FIG. 5 has mainly the same advantages as described with reference to the double ball-armature relay shownin FIG. 2 if use is made of contact strips formed from acomb of strip material and also of two permanent magnets or of one annular magnet common to the various contacts.

The permanent magnets in bistable ball-armature contacts according to the invention are polarized in the mounted condition. In the arrangement required for polarizing, the strength of the permanent magnets can also be adjusted while the final inspectionof the ballarmature contact'can-also be'performed in this arrangement. The said combination of measures in the production process results in a price decrease with respect to the described known bistable ball-armature contacts, in particular for series manufacture. in addition the risk of insufficient reliability on account of metal particles on the permanent magnets is precluded.

What is claimed is: V l. A bistable ball-armature switching device accommodated in a hermetically closed envelope comprising, a ball-armature displaceable by a magnetic flux variation between first and second switching positions, first and second permanent magnets arranged to hold the ball-armature in said first and second switching positions respectively, a first electrically conductive contowardsthe supporting strip, each of said ends forming tact strip, a-supporting strip of electrically conducting material for the ball-armature arranged in parallel with said first contact strip and common to both-switching positions, a second electrically conductive contact strip arranged substantially collinear with the first contact strip, said first, and second magnets being arranged cooperatively with said contact strips so that the flux of v the first magnet corresponding to one switching positionpasses mainly through the v.first contact strip and ,thesupport strip whereas the flux of the second permanent magnet corresponding to the other switching position passes mainly through thesecond contact strip and said supporting strip, the permanent magnets-being polarized in the samedirection.

2'. A bistable ball-armature switching device as claimed in claim 1, characterized in that the adjacent ends of the first and-second contact strips are each bent vant switching position.

switching device strip are provided with achamfer near that end which is bent towards the supporting strip.

4. A bistable ball-armature switching device as claimed in claim 1 further comprising a U-shaped strip 7 which is secured to the supporting. strip so that the limbs of said U-shaped'stri'p extend on opposite sides of the ball-armature thereby limiting the movement of the ball armature.

A bistable ball-armature switching device as claimed in claim 2, characterized in that, viewed from the supporting'strip, the center of the ball-armature is situated above the points of abutment of the ball armature with both contact strips.

6. Aswitching device comprising, a ball armature composed of a magnetic and electrically conductive material and selectively displaceable between first and secondpositions by a magnetic flux variation, a support strip for the ball armature composed of electrically conductive material, first and second electrically conductive contact strips linearly arranged parallel to the support strip with adjacent ends forming a gap for the ball armature, a first permanent magnet located on the same side of the ball armature as the first contact strip, a second permanent magnet polarized in the same directionfas the first magnet and located on the opposite side of the ball armature and corresponding to the second contact strip, said first and second magnets being operative to hold the ball armature in said first and second positions,respectively, in the absence of an external magnetic flux, and means selectively. providing a magneticflux variation to selectively displace the ball armature between said'first and second positions.

7. A switching device as claimed in claim 6 wherein said first magnet is mounted between the support strip and the first contact strip and the second magnet is mounted between the support strip and the second contact strip, said first position corresponding-to the ball armature in contact with the support strip and the first contact strip and the second position corresponding to the ball armature in contact with the support'strip and the second contact strip.

8. A switching device as claimed in claim 6 wherein the ends of the contact strips facing the ball armature, are each bent in the direction of the support strip to form first and second abutment members for the ball armature corresponding to said first and second positions, respectively. I

9. A switching device as claimed in claim 8 wherein said facing ends of the first and second contact strips include diagonally opposed chamfers.

10. A switching device as claimed in claim 6 further comprising a U-shaped member securedto the support strip in the vicinity of said gap and with its limbs extending on opposite sides of the ball armature so as to limit lateral movement thereof.

1 l. A switching device as claimed in claim 6 wherein the facing ends of the first and second contact strips form first and second abutment members for the ball armature which correspond to said first and second positions, respectively, said magnets being located on opposite sides of the ball armature and said contact strips are located on one side of the magnets and said support strip on the other side of the magnets and parallel to the contact strips, and wherein the center of the ball armature is located above the points of abutment of the ball armature with said contact strips. a: 3k 

1. A bistable ball-armature switching device accommodated in a hermetically closed envelope comprising, a ball-armature displaceable by a magnetic flux variation between first and second switching positions, first and second permanent magnets arranged to hold the ball-armature in said first and second switching positions respectively, a first electrically conductive contact strip, a supporting strip of electrically conducting material for the ball-armature arranged in parallel with said first contact strip and common to both switching positions, a second electrically conductive contact strip arranged substantially collinear with the first contact strip, said first and second magnets being arranged cooperatively with said contact strips so that the flux of the first magnet corresponding to one switching position passes mainly through the first contact strip and the support strip whereas the flux of the second permanent magnet corresponding to the other switching position passes mainly through the second contact strip and said supporting strip, the permanent magnets being polarized in the same direction.
 1. A bistable ball-armature switching device accommodated in a hermetically closed envelope comprising, a ball-armature displaceable by a magnetic flux variation between first and second switching positions, first and second permanent magnets arranged to hold the ball-armature in said first and second switching positions respectively, a first electrically conductive contact strip, a supporting strip of electrically conducting material for the ball-armature arranged in parallel with said first contact strip and common to both switching positions, a second electrically conductive contact strip arranged substantially collinear with the first contact strip, said first and second magnets being arranged cooperatively with said contact strips so that the flux of the first magnet corresponding to one switching position passes mainly through the first contact strip and the support strip whereas the flux of the second permanent magnet corresponding to the other switching position passes mainly through the second contact strip and said supporting strip, the permanent magnets being polarized in the same direction.
 2. A bistable ball-armature switching device as claimed in claim 1, characterized in that the adjacent ends of the first and second contact strips are each bent towards the supporting strip, each of said ends forming an abutment member for the ball-armature in the relevant switching position.
 3. A bistable ball-armature contect as claimed in claim 2, characterized in that the first and the second switching device strip are provided with a chamfer near that end which is bent towards the supporting strip.
 4. A bistable ball-armature switching device as claimed in claim 1 further comprising a U-shaped strip which is secured to the supporting strip so that the limbs of said U-shaped strip extend on opposite sides of the ball-armature thereby limiting the movement of the ball armature.
 5. A bistable ball-armature switching device as claimed in claim 2, characterized in that, viewed from the supporting strip, the center of the ball-armature is situated above the points of abutment of the ball armature with both contact strips.
 6. A switching device comprising, a ball armature composed of a magnetic and electrically conductive material and selectively displaceable between first and second positions by a magnetic flux variation, a support strip for the ball armature composed of electrically conductive material, first and second electrically conductive contact strips linearly arranged parallel to the support strip with adjacent ends forming a gap for the ball armature, a first permanent magnet located on the same side of the ball armature as the first contact strip, a second permanent magnet polarizEd in the same direction as the first magnet and located on the opposite side of the ball armature and corresponding to the second contact strip, said first and second magnets being operative to hold the ball armature in said first and second positions, respectively, in the absence of an external magnetic flux, and means selectively providing a magnetic flux variation to selectively displace the ball armature between said first and second positions.
 7. A switching device as claimed in claim 6 wherein said first magnet is mounted between the support strip and the first contact strip and the second magnet is mounted between the support strip and the second contact strip, said first position corresponding to the ball armature in contact with the support strip and the first contact strip and the second position corresponding to the ball armature in contact with the support strip and the second contact strip.
 8. A switching device as claimed in claim 6 wherein the ends of the contact strips facing the ball armature are each bent in the direction of the support strip to form first and second abutment members for the ball armature corresponding to said first and second positions, respectively.
 9. A switching device as claimed in claim 8 wherein said facing ends of the first and second contact strips include diagonally opposed chamfers.
 10. A switching device as claimed in claim 6 further comprising a U-shaped member secured to the support strip in the vicinity of said gap and with its limbs extending on opposite sides of the ball armature so as to limit lateral movement thereof. 